What is the age range for the Graco Jumpster?

My sister will be one on Sunday. I thought about getting her a Graco Jumpster. Shown here: a href="http://www.toysrus.com/product/index.jsp?productId=2564010" rel="nofollow"http://www.toysrus.com/product/index.jsp…/a It says for babies up to twenty five pounds. My sister is about 18 pounds or so. But what is the age range? I heard it would not be suiteable for a child her age.